1. Field of the Invention
The present invention generally concerns hydrofoil watercraft, including both large extended-performance hydrofoil watercraft (E-P HFWC) as are currently under study and evaluation by the military, and personal hydrofoil watercraft (P HFWC) such as have previously been used in recreation.
The present invention particularly concerns extended-performance hydrofoil watercraft (E-P HFWC) that, nonetheless to having hydrofoils that are positionally fixed in extension from the hull, are safe and stable to operate in shallow water, and also in heavy seas when not on hydrofoil plane or when progressing to hydrofoil plane. The present invention also particularly concerns the configuration of smaller, personal, versions of hydrofoil watercraft (P HFWC) so as to be fast and highly maneuverable, including so as to jump free of the water, nonetheless to being (i) stable and pleasant to operate at slower speeds and even to sit upon when stopped, (ii) relatively economical of construction and operation, and (iii) relatively quickly and easily launched, recovered, and transported on land.
2. Description of the Prior Art
2.1 Adjustable (Outboard) Pontoons, or Sponsons PA0 2.2 Accommodations of Hydrofoil Watercraft to Operation in Shallow Water
A first aspect of the present invention will be seen to concern floats, or pontoons, or sponsons that are moveable relative both to the main body of a hydrofoil watercraft (HFWC)--including personal hydrofoil watercraft (P HFWC)--and relative to the water in which the hydrofoil watercraft (HFWC) float.
Moveable floats, or pontoons, or sponsons are known in the prior art, including for application to hydrofoil watercraft (HFWC). The sponsons have typically been moveable between (i) positions in the water where hydrostatic or hydrodynamic stability is provided to the HFWC (respectively depending upon whether the HFWC is stationary or moving), and (ii) positions out of the water where--at least occasionally--aerodynamic stability has been imparted to a moving watercraft.
The present invention will later be seen to deploy moveable floats, or pontoons, or sponsons and their associated supporting structures on HFWC including P HFWC. So deployed, the sponsons serve at least three additional, new, purposes to the stabilizing purposes of the prior art.
First, differing sponson positions in the present invention will be seen to accord a very considerably different HFWC flotation. This differing flotation affects, in particular, the depth below water surface of both the hydrofoils and any propeller, or other in-water propulsion mechanism, of the HFWC. In general the sponsons of the prior art, regardless to what type of watercraft applied, have not had such significant displacement, and flotation, so as to affect by their variable positions the waterline of the entire watercraft.
Second, the sponsons of HFWC and P HFWC in accordance with the present invention will be seen to provide, selectively with differing positions of the moveable sponsons and their supporting structure, a ramp surface that helps the HFWC and P HFWC to go onto plane much sooner and slower, and with much less energy, than otherwise. This ability of the moveable sponsons to function as part of the planning hull is a function of (i) their size and bulk, (ii) their positions, (iii) their contours, and (iv) their moveability. Such a function for moveable sponsons is not known to the inventors to be within the prior art.
Third, the sponsons of certain larger, extended performance HFWC, in accordance with the present invention will be seen to expose, in certain positions, an inner, or core, hull to the HFWC. Because of the manner by which the HFWC is lifted on its moveable sponsons and it foils, it is structurally suitable that this inner hull may have a watertight door without hazarding the safety of the vessel. When the HFWC is stopped at sea, or on a beach, or at a pier, then (i) the sponsons may be positioned laterally extended from the core hull, and (ii) this door may be opened to provide excellent access to the interior of the ships hull.
Non-hydrofoil watercraft having moving pontoons that are adjustable on hinged arms in their extension into the water from the body of the watercraft are shown, inter alia, in U.S. Pat. Nos. 3,485,198 for a BOAT WITH FLOTATION SPONSONS; 4,669,408 for an AMPHIBIOUS JET POWERED CRAFT, and 4,875,426 for a FLOAT ATTACHMENT FOR WATERCRAFT. Adjustable outboard "pontoons" are called "sponsons".
A watercraft using stabilizing foils and floats, or sponsons, is shown in U.S. Pat. No. 4,452,166 for a FOIL STABILIZED MONOHULL VESSEL. The vessel leaves its hydrofoils fixed in position while the watercraft is stabilized in the water by the repositioning of floats, or sponsons. The floats are intended to rest upon the water when the vessel is at rest or low speeds, and to be removed from the water (the stabilization function being more substantially assumed by the adjustable foils) when the vessel is at high speeds.
Personal hydrofoil watercraft again using moveable floats, or sponsons, for purposes of stabilization are shown in U.S. Pat. No. 3,294,055 for a WATERCRAFT and U.S. Pat. No. 4,964,357 for a PLANING BOAT.
The hydrofoil(s) and the propulsion drive assembly(ies) of a hydrofoil watercraft (HFWC) necessarily extend (at least when the watercraft is operative) into the water below the hull of the HFWC. These extensions present challenges to the (i) operation of the HFWC in shallow water, (ii) maneuvering of the HFWC in shallow water whether or not under its own power, and/or (iii) pulling of the HFWC up an inclined ramp onto land or onto a land transport trailer or vehicle. "Shallow water" is defined as any water insufficiently deep so as permit an adequate safe clearance between the bottom and either or both of the hydrofoil(s) and/or the propulsion drive assembly(ies) of the HFWC when the HFWC is (i) either loaded or unloaded and (ii) either moving or stationary within the water.
A common solution to safely bringing a HFWC having downwards extending hydrofoils and/or propulsion assemblies into shallow water is to mechanically raise these assemblies relative to the hull of the HFWC. The required raising is accomplished by diverse forms of mechanical assemblies including mechanisms for linear retraction and for hinged swinging. Because a hydrofoil assembly must be sufficiently robust so as to at least partially support the weight of the HFWC when the HFWC is on hydrofoil plane, and because the propulsion assembly of the HFWC must be sufficiently robust so as to deliver the force propelling the HFWC through the water (including at speeds causing the watercraft to go onto hydrofoil plane), both hydrofoil and propulsion assemblies are typically relatively massive and strong, and are normally made from steel. Creating moveable or hinged mounts for these massive assemblies normally requires commensurately strong, and expensive, mechanical sub-assemblies.
The present invention will be seen to reject the approach of mechanically raising the hydrofoil(s) and/or the propulsion drive assembly(ies) of a HFWC during use of such HFWC in, or the transport of HFWC through, shallow water, or during the extraction of HFWC along a ramp from water (that is necessarily shallow at the foot of the ramp) onto land. Instead of raising either or both its hydrofoil(s) and/or its propulsion drive assembly(ies), a powered HFWC in accordance with the present invention will be seen to leave both these assemblies absolutely fixed in position (at least as regards in their extension below the hull of the HFWC). Instead of raising its hydrofoil(s) and/or its propulsion drive assembly(ies), a HFWC in accordance with the present invention will be seen to effectively "enlarge the hull", therein increasing its buoyancy and floating the hull higher in the water. Consequently to the hull floating higher in the water the hydrofoil(s) and the propulsion assembly(ies) that are (fixedly) connected to the hull also float higher in the water. In fact, they float so high that, while still in the water, they are no longer constitute the lowermost extension of the HFWC.
Exactly how this "enlargement of the hull" is accomplished will be taught later in this specification. The hull is normally so effectively "enlarged" by use of floats (or pontoons, or sponsons) and/or gas bags. Therefore the use of HFWC in shallow water, and the extraction of such HFWC onto land, will, in the present invention, prove to be related to the sponsons discussed in the previous section 2.1. For the moment, however, it is sufficient to understand that, while moveable floats (including moveable floats in the form of sponsons) are known for use with watercraft, including for HFWC, the sponson-type floats of the present invention are used in a manner, position and degree to which is, to the best knowledge of the inventors, unlike the purposes for which, and the ranges over which, any of floats, pontoons or sponsons have previously been used.